DISCOVERING CHEMISTRY YOU NEED TO KNOW

KENDALL/HUNT PUBLISHING COMPANY4050 Westmark Drive Dubuque, Iowa 52002 Kelly Deters

D I S C O V E R I N G C H E M I S T R Y Y O U N E E D T O K N O W

Copyright © 2009 by Kendall Hunt Publishing Company

ISBN 978-0-7575-5236-6

Cover photos: Background periodic table image © Michael D Brown, 2008. Under license from Shutterstock, Inc. Photo of girl and boy ©Corbis. Background honeycomb chemistry image © mtr, 2008. Under license from Shutterstock, Inc.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the copyright owner.

Printed in the United States of America

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Discovering Chemistry You Need to Know �

Preface ............................................................................................................................................. xvi

To the Student ....................................................................................................................... xviii

Chapter 1 Scientists’ Tools .................................................................................. 1Section 1.1: Doing Science .........................................................6 There’s more to science than experimentation ..................................7Two types of experiments ......................................................................7Variables and constants .........................................................................8Predictions and hypotheses ...................................................................8Designing procedures ............................................................................9Gathering data ........................................................................................9Drawing conclusions—Theories and laws ........................................11Communicating findings ....................................................................11You as a scientist ...................................................................................11Section 1.2: Observations and Measurements ...................13 Taking observations ............................................................................14Gathering data ......................................................................................14Uncertainty in measurement and choosing the right tool ..............15Relative error .........................................................................................15Number of decimal places to record ..................................................16Section 1.3: Designing Your Own Labs ..................................18Identifying the purpose, problem, or question .................................18Gathering background information...................................................18Designing the results, calculations, and data table ..........................19Writing the procedure .........................................................................19Determining the materials needed and writing safety concerns ...19Making changes to prewritten procedures ........................................20Discussing results .................................................................................20Section 1.4: Converting Units ....................................................23Dimensional analysis ...........................................................................23Dimensional analysis steps ..................................................................24Metric conversions ...............................................................................25Help with metric prefixes ....................................................................25Volume units .........................................................................................25Converting with multiple steps ..........................................................25Section 1.5: Significant Digits ..................................................27Rules for counting significant digits ..................................................27

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Performing calculations with significant digits ................................28Rules for math with significant digits ................................................29Section 1.6: Scientific Notation ...............................................30Rules for using scientific notation ......................................................30Summary ............................................................................................32Review .................................................................................................33

Chapter 2 Antacids ......................................................................................................34Section 2.1: Types of Matter ......................................................38Classifying pure substances.................................................................38Classifying mixtures .............................................................................38Section 2.2: Naming Chemicals ................................................41Writing the names of ionic compounds ............................................41Writing molecular compound names ................................................46Molecules with common names .........................................................47Writing element names ........................................................................47Section 2.3: Writing Chemical Formulas ...............................48Writing ionic compound formulas ....................................................48Molecular compounds .........................................................................50Writing diatomic element formulas ...................................................51Section 2.4: Defining, Naming, and Writing Acids and Bases ...............................................................................51Naming acids ........................................................................................52Writing acid formulas ..........................................................................52Bases .......................................................................................................54Section 2.5: Characteristics of Acids and Bases ...............56Strength versus concentration of acids and bases ............................57pH scale .................................................................................................58Measuring pH .......................................................................................59Section 2.6: Chemical Reactions .............................................59Examples of chemical equations .........................................................59Parts of a chemical equation ...............................................................60Double replacement and neutralization reactions ...........................61Section 2.7: Balancing Chemical Reactions ........................63Law of conservation of mass/matter ..................................................64Balancing chemical equations ............................................................64Section 2.8: Speeding Up Chemical Reactions ...................67Collision theory ....................................................................................68

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Catalysts speed up reactions ...............................................................71Summary ............................................................................................74Review .................................................................................................75

Chapter 3 Airbags ........................................................................................................ 78Section 3.1: States of Matter ...................................................82Properties of three states of matter ....................................................82Changes in state ....................................................................................83What’s between the molecules? ..........................................................84Section 3.2: Properties of Matter ...........................................85Physical and chemical properties .......................................................85Intensive and extensive properties .....................................................85Section 3.3: Density .....................................................................87Density units .........................................................................................88Density graphs ......................................................................................88Floating and layers ...............................................................................89Section 3.4: Changes in Matter ...............................................92Physical changes ...................................................................................94Chemical changes .................................................................................94Common misconceptions concerning changes ...............................94Section 3.5: Gas Behavior ...........................................................95Gases exert pressure .............................................................................95Changes in gases result in changes in pressure ................................96Kinetic molecular theory .....................................................................97Real versus ideal gases .........................................................................97Diffusion and effusion .........................................................................98Section 3.6: Counting Molecules .......................................... 100The mole ............................................................................................. 100Atomic and molecular masses ......................................................... 102Molecular mass is used to convert between moles and grams .... 103Section 3.7: Gas Laws ............................................................... 105Converting units of pressure ............................................................ 107Temperature units used when working with gas laws .................. 108Avogadro’s gas law ............................................................................. 108Charles’ gas law .................................................................................. 108Boyle’s gas law .................................................................................... 109Combined gas law ............................................................................. 109Ideal gas law ....................................................................................... 110

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Choosing the appropriate law .......................................................... 110Standard temperature and pressure (STP) ..................................... 110Summary ......................................................................................... 116Review .............................................................................................. 117

Chapter 4 Glowing Things ................................................................................. 120Section 4.1: Development of Atomic Theory ...................... 124Dalton’s atomic theory ...................................................................... 124Discovering the fundamental particles of the atom ...................... 125Refining the atomic theory further ................................................. 126Modern atomic theory ...................................................................... 127Section 4.2: Atomic Structure ................................................ 128Protons in the atom ........................................................................... 128Mass number and neutrons in the atom ........................................ 128Isotopes—Atoms of the same element can be different ............... 131Section 4.3: Electron Structure ............................................. 134Electron levels, subshells, and orbitals ............................................ 135Showing electron configurations ..................................................... 137Section 4.4: Periodic Table ...................................................... 139The modern periodic table ............................................................... 140Electron configurations and the periodic table ............................. 141Periodic table as a map for electron configurations ...................... 142Section 4.5: Periodicity ............................................................. 144Atomic radius ..................................................................................... 145Ionization energy ............................................................................... 146Electron affinity ................................................................................. 146Ion radius ............................................................................................ 147Section 4.6: Light ........................................................................ 148Wave properties ................................................................................. 148Energies and colors of visible light .................................................. 149Section 4.7: Light and Matter ................................................. 150Light interaction with matter ........................................................... 151Quantization of photons and absorption by electrons ................. 152Step-wise relaxation .......................................................................... 153Measuring light’s interaction with matter ...................................... 154Ways of producing light .................................................................... 155Summary ......................................................................................... 158Review .............................................................................................. 159

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Chapter 5 Soap ........................................................................................................... 160Section 5.1: Types of Bonds ................................................... 164Bonding between metals and nonmetals ....................................... 164Bonding between nonmetals ........................................................... 165Bonding between metals ................................................................. .165Characteristics of different types of bonds ..................................... 166Melting and boiling points ............................................................... 166Solubility in water .............................................................................. 166Conduction of electricity .................................................................. 166Section 5.2: Drawing Molecules ........................................... 170Determining valence electrons ........................................................ 170Placing the electrons around the symbol ....................................... 170Lewis dot structures for ionic compounds ..................................... 171Lewis structures for covalent compounds ...................................... 173Lone pairs ........................................................................................... 174Lewis structures that can be written more than one way ............. 176Lewis dot structures for polyatomic ions ....................................... 178Exceptions to the octet rule ............................................................. .179Section 5.3: Molecules in 3D ................................................ 181Geometry of covalent bonding ........................................................ 182Distortion of angles with lone pairs ................................................ 182Ionic compound structures .............................................................. 182Section 5.4: Polarity of Molecules ...................................... 183Electronegativity and the periodic table ......................................... 183Electronegativity and polarity of bonds ......................................... 184Polarity of bonds and polarity of molecules .................................. 185Section 5.5: Intermolecular Forces ..................................... 186Intramolecular versus intermolecular forces ................................. 186London dispersion forces ................................................................. 186Dipole–dipole interactions ............................................................... 187Hydrogen bonding ............................................................................ 187Section 5.6: Intermolecular Forces and Properties ...... 188Melting, evaporating, and boiling ................................................... 189Importance of water’s intermolecular forces to life ....................... 190Viscosity .............................................................................................. 190Solubility ............................................................................................. 190Oil and water ...................................................................................... 191How soap affects solubility ............................................................... 191Surface tension ................................................................................... 192

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Effect of soap on surface tension ..................................................... 193Summary ......................................................................................... 198Review .............................................................................................. 199

Chapter 6 Sports Drinks .................................................................................... 202Section 6.1: Solutions and Electrolytes .............................. 207How ionic compounds dissolve in water ........................................ 207A misconception about dissolving .................................................. 208Forming electrolytes in water .......................................................... 208Clarification of terms ........................................................................ 209Making a solution .............................................................................. 210Section 6.2: Concentrations of Solutions .......................... 212Percent concentration ...................................................................... 212Molarity concentration .................................................................... 213Converting between %(W/V) and molarity .................................. 213Concentration of electrolytes ........................................................... 214Section 6.3: Acidity and pH ..................................................... 216Calculating pH from concentration of hydronium ...................... 216Solving for concentration of hydronium ........................................ 218Strength of acids and pH .................................................................. 218Bases .................................................................................................... 219Acids and bases are electrolytes ....................................................... 220Autoionization of water .................................................................... 220Section 6.4: Solubility and Precipitation ............................ 221Precipitation reactions ...................................................................... 223Solubility of ionic compounds ......................................................... 223Solubility rules ................................................................................... 223Section 6.5: Stoichiometry ...................................................... 225Mole ratio in a balanced chemical equation .................................. 226Molecular mass and finding moles for stoichiometry .................. 227Molarity and finding moles for stoichiometry .............................. 228Combining molecular mass and molarity in stoichiometry problems ........................................................... 229Stoichiometry with gases .................................................................. 229Keeping equalities straight ............................................................... 230Titration .............................................................................................. 230Percent yield ....................................................................................... 231Section 6.6: Limiting Reactants ............................................ 236Limiting and excess reactants .......................................................... 237

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Section 6.7: Properties of Solutions .................................... 239Vapor pressure ................................................................................... 240Vapor pressure of a solution ............................................................. 241Effects of electrolyte versus non-electrolyte solutes ...................... 241Boiling point of a solution ................................................................ 242Calculating boiling point of an aqueous solution ......................... 242Freezing point of a solution ............................................................ 243Calculating freezing point of an aqueous solution ....................... 244Summary ......................................................................................... 247Review .............................................................................................. 248

Chapter 7 Hot and Cold Packs .................................................................... 250Section 7.1: Endothermic and Exothermic ......................... 254System versus surroundings ............................................................. 254Endothermic processes ..................................................................... 255Exothermic processes ....................................................................... 255Section 7.2: Calorimetry and Heat Capacity ..................... 256Heat, energy, and enthalpy ............................................................... 256Units for measuring energy .............................................................. 257Heat capacity ...................................................................................... 257Using heat capacity in calculations ................................................. 258Calorimetry ........................................................................................ 261Section 7.3: Changes in State ................................................ 263Temperature does not change during change in state .................. 263Enthalpy changes during change in state ....................................... 264Heating curves—adding energy to a substance ............................. 265Cooling curves—removing energy from a substance ................... 266Section 7.4: Enthalpy of a Chemical Reaction ................. 269Enthalpy of formation ....................................................................... 269Enthalpy of reaction .......................................................................... 270Taking into account the number of moles of the compound in the reaction ........................................................................... 271Enthalpy and stoichiometry ............................................................. 272Section 7.5: Hess’s Law ............................................................ 275Steps for completing a Hess’s law problem ..................................... 275Summary ......................................................................................... 280Review .............................................................................................. 281

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Chapter 8 Chemistry in Industry ............................................................... 282Section 8.1: Equilibrium ........................................................... 286Reversible reactions ........................................................................... 286Establishing equilibrium .................................................................. 287Dynamic equilibrium ........................................................................ 288Determining whether a system is at equilibrium .......................... 289Section 8.2: Equilibrium Constants ...................................... 289Writing equilibrium constant expressions ..................................... 290Not all reactants and products are included in the equilibrium constant expression ............................................. 290Using equilibrium constant expressions in calculations .............. 291Units of equilibrium constants ........................................................ 292Meaning of an equilibrium constant ............................................... 292Equilibrium constants and temperature ......................................... 293Section 8.3: Reaction Quotients ............................................ 297Reaction quotient .............................................................................. 298Which way to go to get to equilibrium ........................................... 298Section 8.4: Le Chatelier’s Principle ................................... 299Le Chatelier’s principle ..................................................................... 301Effect of changing concentrations ................................................... 301Effect of changes in volume (changes in pressure) ....................... 302Effect of changing temperature ........................................................ 303When changes do not disturb the equilibrium .............................. 304Speeding up the time it takes to reach equilibrium ...................... 304Section 8.5: Environmental Concerns ................................. 305Earth .................................................................................................... 305Air ........................................................................................................ 309Ozone .................................................................................................. 310Greenhouse gases and global warming .......................................... 311Your job ............................................................................................... 312Summary ......................................................................................... 314Review .............................................................................................. 315

Chapter 9 Forensic Chemistry ..................................................................... 316Section 9.1: Analysis Using Solubility ................................. 320What substances will dissolve in water? ......................................... 320Dissolving a substance and equilibrium ......................................... 321

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Writing equations and equilibrium constant expressions for dissolving a substance .............................................................. 322Determining whether a substance will precipitate out ................. 324Precipitation reactions ...................................................................... 326Using solubility information for analysis of a sample ................... 327Qualitative and quantitative analysis .............................................. 327Section 9.2: Analysis Using Chromatography ................... 330Paper chromatography...................................................................... 330Thin layer chromatography .............................................................. 332Liquid chromatography .................................................................... 332Gas chromatography ......................................................................... 333Section 9.3: Analysis of a Chemical Formula ................... 337Percent composition ......................................................................... 337Empirical formulas ............................................................................ 339Molecular formulas ........................................................................... 340Hydrates .............................................................................................. 344Hydrate formulas ............................................................................... 344Summary ......................................................................................... 348Review .............................................................................................. 349

Chapter 10 Batteries ................................................................................................ 350Section 10.1: Reduction and Oxidation .............................. 354Defining reduction and oxidation ................................................... 354Reduction and oxidation happen simultaneously ......................... 355Determining oxidation number ...................................................... 355Identifying what element is being reduced or oxidized in a reaction ........................................................................................ 356Oxidizing agent and reducing agent ............................................... 357Section 10.2: Redox Reactions .............................................. 358Single replacement reactions ........................................................... 358Activity series ..................................................................................... 360Balancing redox reactions ................................................................ 362Balancing redox reactions in an acidic solution ............................ 362Balancing redox reactions in a basic solution ................................ 364Section 10.3: Batteries and Redox Reactions .................. 366Voltaic cells ......................................................................................... 366Line notation ...................................................................................... 367Calculating cell potential .................................................................. 370Standard reduction potentials.......................................................... 370

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Cell potential ...................................................................................... 370Standard reduction potential is an intensive property ................. 371Nonstandard cells .............................................................................. 371Concentration cells ........................................................................... 372Electrolytic cells ................................................................................. 373Summary ......................................................................................... 376Review .............................................................................................. 377

Chapter 11 Polymers ................................................................................................. 378Section 11.1: Hydrocarbons .................................................... 382Alkanes ............................................................................................... 383Alkenes ............................................................................................... 384Isomers ................................................................................................ 384Alkynes ............................................................................................... 385Alkene/alkyne isomers...................................................................... 386Saturation of hydrocarbons .............................................................. 386Hydrocarbon side branches ............................................................. 387Section 11.2: Organic Functional Groups .......................... 389Haloalkanes ........................................................................................ 389Alcohols .............................................................................................. 390Ethers .................................................................................................. 391Amines ................................................................................................ 392Carbonyl-containing compounds ................................................... 392Aromatic compounds ....................................................................... 395Section 11.3: Polymers ............................................................. 398Thermoplastic versus thermoset polymers .................................... 399Reactions forming polymers ............................................................ 399Properties of polymers ...................................................................... 401Polymers in biological settings ........................................................ 402Summary ......................................................................................... 407Review .............................................................................................. 408

Chapter 12 Nuclear Radiation ........................................................................ 410Section 12.1: Nuclear Reactions ........................................... 414Discovery of nuclear radioactivity .................................................. 414What is nuclear radioactivity? ......................................................... 414Types of radioactive decay ............................................................... 416Nuclear reactions and equations ..................................................... 417Half-lives ............................................................................................. 419

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Section 12.2: Nuclear Radiation: Harmful or Helpful? . 422Effects of radiation on the body ...................................................... 422Nuclear dating .................................................................................... 425Energy—fission versus fusion .......................................................... 426Summary ......................................................................................... 428Review .............................................................................................. 429

Appendices ................................................................................................................................ 430A. Units & Measurement ........................................................................................ 430

Quantities Commonly Measured in Chemistry .................................................... 430Common Equivalents ................................................................................................ 430Unit Abbreviations .................................................................................................... 430Metric Prefixes ........................................................................................................... 430Symbols ....................................................................................................................... 431State Symbols .............................................................................................................. 431

B. Writing and Naming Formulas .......................................................................... 432Common Polyatomic Ions ........................................................................................ 432Common Multivalent Metals and Their Charges .................................................. 433Prefixes Used in Molecular Compounds ................................................................ 433Diatomic Elements and Formulas ........................................................................... 433Organic Nomenclature Prefixes ............................................................................... 433

C. Solubility .................................................................................................................. 434Solubility Rules ........................................................................................................... 434Solubility Product Constants (25°C) ....................................................................... 434Compound Solubility ................................................................................................ 435

D. Useful Constants .................................................................................................. 436Equilibrium ................................................................................................................ 436

E. Electrochemistry ................................................................................................... 437Activity Series ............................................................................................................. 437Reduction .................................................................................................................... 437

F. Enthalpies of Formation (Hf) kJ/mole ........................................................... 438G. The Elements .......................................................................................................... 440

Name, Symbol, Atomic Number, Atomic Mass ....................................................... 440Element Properties ...................................................................................................... 443Periodic Table ............................................................................................................. 444

Glossary ........................................................................................................................................ 445

Index ................................................................................................................................................. 451

Photo Credits .......................................................................................................................... 461

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Why I Wrote This Textbook, and How It’s Different from Other Textbooks I wrote this textbook for my students! I wanted my students to see how chemistry applies to their lives and to see it as concepts that are interconnected. They have loved it and I hope you will, too.

Other chemistry textbooks have each “concept” as a separate chapter. The problems with these textbooks include: (1) students see chemistry as a group of separate concepts rather than seeing the interconnections between the different ideas; (2) students don’t see the application to their lives (the “application” is often placed in sidebars that students don’t read); and (3) students don’t feel like they’re “doing science.”

This textbook is different. It presents the information as scientists learn it. Scientists presented with a new problem or challenge would seek out the information they need in order to study or solve a problem and apply it to that situation. This textbook is centered around twelve real-life themes and the chemistry needed to understand each theme. Concepts are not artificially introduced—only those that are needed to understand the theme are covered in that chapter. This allows you to see the relevance of every concept you study.

Additionally, this textbook includes “inquiry” labs—which is the science-education term used when students design their own procedures. Inquiry labs are included at least once in every chapter. They include lots of instruction in the beginning, but by the end students are so competent at lab design that I provide a mere list of things to include in the write-up. This will help you develop scientific process skills and allow you to “do science” yourself.

Why I Chose This TitleThe title Discovering Chemistry You Need to Know has two meanings. First, the content is introduced in a need-to-know format. This means that you learn the chemistry concepts that you “need to know” in order to understand each theme. Second, since I’ve been using this way of teaching with my students, I’ve never once been asked, “When are we ever going to need to know this?” Instead, students have eagerly asked what the next theme will be and gone home to share with their family how an airbag, or some other theme, works.

AcknowledgmentsI’d like to thank the many people who have helped me along the way. First, my husband, Luke, who supported the writing of a book that came out of the blue, without ever saying I was crazy. My chemistry teacher and mentor, Sue Rusco (now retired), was a wonderful influence, and my mom, Dr. Frances Morgan (a chemist herself) both opened up an exciting world of color and reactions, and supported my every leap over the years. Thanks to my dad, Roger Morgan, who always lets me know how proud he is. Dr. Howard Drossman first introduced me to thematic teaching and gave me my start in curriculum development. He told me he believed that one day I’d change the way chemistry is taught. I hope I’m reaching that day! Thank you, Dr. Paul Kuerbis, for introducing me to inquiry.

My publisher, Kendall/Hunt, and their former science editor, Troy Jacobsen, supported my efforts financially with field testing and guided this project through publication. Thanks also to Lynn Molony, Victoria Noel, Beth Trowbridge, Kelly Heinrichs,

Discovering Chemistry You Need to Know x�ii

Charmayne McMurray, Dennis Jaeger, and many others who helped bring this project to print.

I’d like to thank the students who acted as guinea pigs for this book over the last few years. They cheerfully went with the flow and were a constant source of support and motivation. All my colleagues (some of whom I’ve never met face-to-face) have provided tremendous support and encouragement.

This text wouldn’t be what it is without the invaluable help of the field test and pilot teachers (listed below) and their students. They were willing to try this innovative project and have had wonderful responses from it. I thank them for their time, effort, and attention to detail, especially Craig Pierson, who went above and beyond the call of duty to support this project.

Field Test TeachersSteve Freers, Temescal Canyon High School, Lake

Elsinore, CAPat Hoffman, East High School, Sioux City, IAMelissa Nielsen, Olathe East High School,

Olathe, KSCraig Pierson, Ph.D., Billings Central Catholic

High School, Billings, MTPaula Roberts, Hillsboro High School,

Hillsboro, ORJeff Venable, Northwestern High School,

Rock Hill, SC

Pilot TeachersKaren Ahrens, Immaculate Heart High School,

Tucson, AZRyan Bleth, Bismarck High School, Bismarck, NDJudy Hom Cheng, Riverdale Country School,

Riverdale, NYAdela J. Dziekanowski, Montville Township High

School, Montville, NJSheri Furby, Monsignor Kelly Catholic High

School, Beaumont, TXCatherine Gammage, Melvindale High School,

Melvindale, MILisa Glass, New Garden Friends School,

Greensboro, NCLeigh Grass, Central Aroostook High School, Mars

Hill, MEValerie Smallbeck, Bismarck High School,

Bismarck, NDRichard Smith, Buena High School, Ventura, CACarolyn Stonecipher, Monsignor Kelly Catholic

High School, Beaumont, TXAndrew Wood, East Butler Public School,

Brainard, NE

x�iii   Discovering Chemistry You Need to Know

Tips for Using This TextHow to Use the ExamplesThe examples in this text fall directly after concepts and calculations are introduced and explain how to do that type of problem. Please don’t skip those boxes! There’s valuable information in them.

Here’s how to make the best use of an example:

• Read the paragraphs once all the way through.

• Go through the example and connect it to what was explained in the paragraphs to make more sense of the concepts.

• Look at the example again, if you need to, when working on practice problems.

Test Features That Benefit YouWhat your teacher says in class will make more sense if you’ve read the chapter beforehand. Each chapter’s second page begins with a list of what’s in the chapter. That list will let you know what to expect. Chemistry is a class where you can have a lot of fun, and each chapter has many activities, practice areas, examples, and lab experiments. At the start of your reading, you’ll see a concept map of the chapter’s ideas. Figures, tables, and photos illustrate interesting aspects of the topic. Within the text, key terms are in bold. You’ll find these terms in the glossary. Be sure to pay attention to and follow all safety notes. When studying, you’ll find each chapter summary and review to be helpful. Furthermore, check out the appendices for useful data.

frontmatter chart

Carbon

Chlorine

Sodium

Oxygen

Nitrogen

Hydrogen

Element Color

Atom Colors in Text